Central heating on, hot water off, all normal and controlled by thermostat. Central heating off, hot water on, all normal, radiators cold. Central heating and hot water on, radiators get hotter and cannot be controlled by thermostat until hot water goes off. The lever on 3 way valve gives resistance and can be moved to open when hot water is switched on, and when HW is off and CH on, there is no resistance (which means to me it is operating normally?). I’m no plumber, but it doesn’t make sense. Please help.
